if(1)
  N = 64;
  P = 8;
  % A = 1+rand(N,N);
  % V = 1+rand(N,N);
  A = ones(N,N);
  V = ones(N,N);
  %
  tic; MAT = df_formL(N,P,A,V); toc;
  tic; Tree = df_setup(N,P,MAT); toc;
  f = rand(N*N, 10);
  tic; u = df_solve(N,P,Tree,f); toc;
  err = df_check(N,P,MAT,f,u); fprintf(1,'relative error %d\n',err);
end
